Are my batteries charging properly?

[JimmyLJ71]

I seem to be having problems with my batteries charging

I have a twin system in my LJ71, i believe it is 24v start.

When i first bought the truck i started having trouble starting, we found the battery nearest the cab was shot, changed it, all was well or so i thought.

I have since had a engine fitted, the engine now requiring more power to turn it over again was difficult to start, again i checked the batteries, the one nearest the cab (the new one) was shot, and the other (much larger) was on the way out

So i did the right thing, got on the forum for advice, i was advised to have both batteries the same size and make, done that, bought two new spankers from Halfords.

The batteries stated on them they were fully charged, i checked the voltage and it was over 14v on both.

Right, i thought everything would be ok, still a little difficult to turn over, but i put this down to the new engine.

It has been on my drive for a week or so, was a little slow on turn over to start this morning, took it for a drive, not far, prob 20-30 miles, went to start tonight, flat as a pancake, checked the votage on the batteries, one was 12.75v, and the one nearest the cab was 11.something volts, one charged up within an hour the other is still charging

I do have all my Aux electrics wired to the battery nearest the cab, and the tow hitch man has wired into my Aux fuse box, but all is switched off and nothing connected to tow plug.

H E L P

 

[John_McCartney]

Someone's wired in a short . . .

Or your alternator's stuffed . . .

Or both . . .

 

[JimmyLJ71]

How can i check?

 

[Jimbo4x4]

Check for current in the alt cables with the ignition off and everything else switched off. If there's a current then your alt is drawing back from the battery, meaning it's stuffed. If not then there must be a short somewhere else.

 

[Roger Fairclough]

The KZJ 70 has the same twin battery set-up and has a 12 volt geared starter. I doubt that yours would be 24 volt, but it doesn't matter either way.

You need to charge up both batteries in isolation, ie not connected into the system. Then connect up, but interpose an accurate low current ammeter between the positive terminal and the output wire. DO NOT ATTEMPT TO START THE MOTOR WITH THE AMMETER IN PLACE because the current will fry it. Go through the systems and make certain everything is switched off. This means interior lights, radio etc. With everything disconnected, there should be no reading on the ammeter. If there is, you have a rogue live circuit or short.

Now the fun begins.

Roger

 

[wobbly]

With the engine running, what is the charge shown on either of the batteries.

 

[JimmyLJ71]

Many thanks

i am going to try and do a bit of checking tonight, where do i find the alt cables?

I have a proper multi meter

 

[JimmyLJ71]

OK, this is what i have done so far.

B1 nearest the front of the car
B2 nearest the cab.

Both batteries put on charger, B1 taken off last night B2 taken off early this morning.

Checked the voltage unconnected.
B1 = 12.8v
B2 = 13v

Then i connected them up.
B1 =12.79
B2 =12.98

Checked both positives with the multi meter to see if there was power leakage with ignition off, none what so ever.

Started engine, voltage readings started to alter, left engine running for a while, voltages settled at:
B1 =13.93
B2 =12.90, dropped slightly, this is the battery that always suffers and goes, it dropped a little more than this before it settled, where as the other constantly rose.

Any ideas?

 

[ModelMakerMan]

Have you checked the earths for each battery and connections between the batteries? It could be that there is a dodge connection or wire meaning that there is more resistance on the path to the one battery meaning the other battery is easier to charge.................... hope that makes sense........................ it makes sense in my world but my world is odd!

 

[Jon Wildsmith]

It sounds like your truck may be 12v not 24v, how sure are you about it being 24v? It sounds like the 2nd battery isn't connected to the main electrics so doesn't see any charge from the alternator so whatever is connected to it will eventually drain it. Have you traced the wire from the positive and negative terminals of B2 and what/where do they go to?

 

[JimmyLJ71]

I think looking at it now that it is 12v.

Can't see alot because when i get back from work it is dark.

Checked the earths, they are both ok, the terminal connectors are not great, but they where tight.

I don't know where i would expect to see the alt leads, B1 has other leads coming out of the terminals, B2 does not, only the positive and negative.

Am i right in thinking there must be a relay somewhere that switches the charge between the two like a battery management system? if so maybe that is bust, where would i find it?

 

[Roger Fairclough]

On my twin battery set-up, there is no system to switch charge from one battery to another. This is one reason why the batteries need to be matched.

Roger

 

[JimmyLJ71]

In that case there must be a busted wire or bad connection somewhere

 

[JimmyLJ71]

Right, i have found the problem , i now need the answer please

Changed both my batteries, still going flat, so i thought today i would change the terminals, upon changing the positive terminal on the battery nearest the front of the truck i found the cable didn't quite reach, i undone the removable cable tie, the lead came away in my hand, the other end wasn't connected to anything

Could some one please tell me where it should go

 

[jonkem]

I think that on my 70 the + terminal on the front battery is a link to the + terminal on the back battery. In normal use they work as one big battery so with a broken link you have just one battery working. It still wouldn't be the end of the world if the one working battery was man enough for all the use it gets.

This shows the + cable just looping between the 2 batteries.

 

[JimmyLJ71]

Many thanks,

Confirmed what Roger pm me, problem was because not linked, one battery is being charged, but the other one has the power taken from it and is not being charged, so i had one battery fully charged but not being used and the other drained flat

 

[Birder]

Many thanks,

Confirmed what Roger pm me, problem was because not linked, one battery is being charged, but the other one has the power taken from it and is not being charged, so i had one battery fully charged but not being used and the other drained flat

As normal, Roger is "The man"

 

[JimmyLJ71]

Here here

Lost count how many times he has got me out the do do's

If and when i meet him i am going to buy him a pint, or two ,or three

Thanks Roger

 

[Roger Fairclough]

Shucks guys.

Roger